As computer systems grow in speed and shrink in size, power consumed within the computer per unit volume (power density) increases dramatically. Thus, it becomes evermore important to dissipate the heat generated by components within the computer during operation to ensure that the components remain within their normal operating temperature ranges. This reduces a chance that the components will fail immediately or have too short a lifetime.
In early desktop personal computers, components were passively cooled by radiation or convection, the surfaces of the components themselves interfacing directly with still air surrounding the component to transfer heat thereto. Unfortunately, air is not a particularly good conductor of heat. Therefore, in the early desktop computers, the heated air tended to become trapped, clinging to the components, acting as a thermal insulator and increasing component operating temperature. Eventually, computers were provided with fans to force air over the surfaces of the components, increasing the temperature differential between the surface of the component and the surrounding air to increase the efficiency of hem transfer. The increased temperature differential overcame some of the poor heat-conducting qualities of air.
Of all components in a computer, the microprocessor central processing unit ("CPU") liberates the most heat during operation of the computer. This springs from its role as the electrical center of attention in the computer. Thus, in prior art computers, motherboards were designed to position the CPU in the flow of air from a cooling fan; other heat-producing components were located away from the CPU to afford maximum cooling of the CPU.
As new generations of microprocessors have arrived, however, this relatively simple scheme has become decidedly inadequate, risking destruction of the CPU. It has become common to associate a heat sink with the CPU to increase the heat-dissipating surface area of the CPU for more effective cooling. Such heat sinks have a plurality of heat-dissipating projections or elements on a surface thereof (an "upper surface," for purposes of discussion). Another surface of the heat sink (the "lower surface") is placed proximate the component and a retention clip is employed to wrap around the heat sink, gripping a lower surface of the component with inward-facing projections.
Prior art retention clips are of two varieties. The first has the profile of a staple, having a flattened center section, two downward-turning end portions and two inward-directed projections to grip an underside of the component. The second has a "V" shaped center section, two downward-turning end portions and two inward-directed projections. A center point of the "V" section contacts and urges against the upper surface of the heat sink, cooperating with the projections to hold the heat sink to the component. The remainder of the "V" section does not contact the upper surface of the heat sink.
Heat sinks are provided with an area on the upper surface where the projections are removed to allow the retention clip to lay directly on the base of the heat sink. The projection-less area is made as small as possible to maximize heat sink surface area. The retention clip is therefore substantially recessed in the projections.
Since the retention clip is recessed in the projections, removal of prior art retention clips presents a problem. Both of the above-described prior art clips require a pulling force for removal. The force either had to be applied to the end portions to rotate one projection from its engagement with the underside of the component or to the central portion to bend an end portion, tilting its associated projection and causing its disengagement. In the past, a prying tool, such as a screwdriver, had to be wedged between the clip and the heat sink or component to exert the required force. Because the clip is recessed between the projections of the heat sink, wedging the tool under the clip is difficult. Likewise, it is difficult to wedge a tool under the end portions.
In many applications, the heat sink has a length and width in excess of that of the component to further maximize surface area. In such cases, apertures are provided in the heat sink for receiving the end portions therethrough. With such heat sinks, it is very difficult to wedge a prying tool under the end portions.
What is needed in the art is a heat sink retention clip or apparatus that does not require a prying tool to remove. More specifically, what is needed is a retention apparatus that can be remove by hand.